Remote code is fetched and cached on first execution, and never updated until the code is run with the --reload flag. (So this will still work on an airplane. See ~/.deno/src for details on the cache.)

File system and network access can be controlled in order to run sandboxed code. Defaults to read-only file system access and no network access. Access between V8 (unprivileged) and Golang (privileged) is only done via serialized messages defined in this

Though JavaScript has the highest number of developers in its community with respect to any other language on earth at this moment; there are a lot of misconceptions, shallow knowledge, bad assumptions among the community members. In this article we have come up with a list of tips, which can make your javascript application faster.

This article is not about dev-ops and doesn’t discuss on things like minify your files or setup redis or use docker and kubernetes to make your application performant. This article is about coding in JavaScript to make the performance better.

I am majorly discussing about JavaScript, but few of the points are related to node.js only, or few may be only for client side JavaScript. However, as majority of the JavaScript developers are full-stack these days, I assume you can understand these easily.

Few weeks ago I noticed a blog post “Oxidizing Source Maps with Rust and WebAssembly” making rounds on Twitter - talking about performance benefits of replacing plain JavaScript in the core of source-map library with a Rust compiled to WebAssembly.

This post piqued my interest, not because I am a huge on either Rust or WASM, but rather because I am always curious about language features and optimizations missing in pure JavaScript to achieve similar performance characteristics.

So I checked out the library from GitHub and departed on a small performance investigation, which I am documenting here almost verbatim.

Before we dive into the details of how TurboFan works, I’ll briefly explain how V8 works on a high level. Let’s have a look at this simplified breakdown of how V8 works (taken from the “JavaScript Start-up Performance” blog post by my colleague Addy Osmani):

resolve and instantiate loader pipeline hooks have been added to the ESM lifecycle #15445

zlib:

CVE-2017-14919 - In zlib v1.2.9, a change was made that causes an error to be raised when a raw deflate stream is initialized with windowBits set to 8. On some versions this crashes Node and you cannot recover from it, while on some versions it throws an exception. Node.js will now gracefully set windowBits to 9 replicating the legacy behavior to avoid a DOS vector.

Earlier this year we published a demo app showcasing our port of Node.js with ChakraCore to iOS. In the accompanying blog article, we talked about how Node-ChakraCore opened a unique opportunity for Node.js to work on iOS, and consequently a path for Node.js to become a viable building block for mobile applications.

The engineering team at Janea Systems has continued to work hard and passionately on this project; so today, we are excited to announce the first alpha release of Node.js for Mobile Apps: a toolkit that enables developers to harvest the power of Node.js and its module ecosystem in their mobile applications. At the heart of it, is a library – available for Android and iOS – that allows an app to host a full-fledged Node.js execution environment. In addition to the core library, we have released plugins for Cordova and React Native – both also compatible with Android and iOS – which make it extremely easy to integrate the Node.js runtime into applications built using on those frameworks.

Proxies have been an integral part of JavaScript since ES2015. They allow intercepting fundamental operations on objects and customizing their behavior. Proxies form a core part of projects like jsdom and the Comlink RPC library. Recently, we put a lot of effort into improving the performance of proxies in V8. This article sheds some light on general performance improvement patterns in V8 and for proxies in particular.

Objects with the same structure (same properties in the same order) have the same HiddenClass

By default every new named property added causes a new HiddenClass to be created.

Adding array-indexed properties does not create new HiddenClasses.

After giving an overview on how V8 uses HiddenClasses to track the shape of objects let’s dive into how these properties are actually stored. As explained in the introduction above, there are two fundamental kind of properties: named and indexed. The following section covers named properties.

In-object vs. Normal Properties: V8 supports so-called in-object properties which are stored directly on the object themselves. These are the fastest properties available in V8 as they are accessible without any indirection. The number of in-object properties is predetermined by the initial size of the object. If more properties get added than there is space in the object, they are stored in the properties store. The properties store adds one level of indirection but can be grown independently.

Objects with the same structure (same properties in the same order) have the same HiddenClass

By default every new named property added causes a new HiddenClass to be created.

Adding array-indexed properties does not create new HiddenClasses.

After giving an overview on how V8 uses HiddenClasses to track the shape of objects let’s dive into how these properties are actually stored. As explained in the introduction above, there are two fundamental kind of properties: named and indexed. The following section covers named properties.

In-object vs. Normal Properties: V8 supports so-called in-object properties which are stored directly on the object themselves. These are the fastest properties available in V8 as they are accessible without any indirection. The number of in-object properties is predetermined by the initial size of the object. If more properties get added than there is space in the object, they are stored in the properties store. The properties store adds one level of indirection but can be grown independently.

Couple of weeks ago we started a series aimed at digging deeper into JavaScript and how it actually works: we thought that by knowing the building blocks of JavaScript and how they come to play together you’ll be able to write better code and apps.

The first post of the series focused on providing an overview of the engine, the runtime and the call stack. This second post will be diving into the internal parts of Google’s V8 JavaScript engine. We’ll also provide a few quick tips on how to write better JavaScript code —best practices our development team at SessionStack follows when building the product.

How the performance characteristics of v8’s Turbofan will affect the way we optimize

Since it’s inception Node.js has depended on the V8 JavaScript engine to provide code execution in the language we all know and love. The V8 JavaScript engine is a JavaScript VM written by Google for the Chrome browser. From the beginning, a primary goal of V8 was to make JavaScript fast, or at least - faster than the competition. For a highly dynamic, loosely typed language this is no easy feat. This piece is about the evolution of V8 and JS engines performance.

Today we are excited to announce the launch of a new JavaScript execution pipeline for V8 5.9 that will reach Chrome Stable in M59. With the new pipeline, we achieve big performance improvements and significant memory savings on real-world JavaScript applications. We’ll discuss the numbers in more detail at the end of this post, but first let’s take a look at the pipeline itself.

The new pipeline is built upon

, V8’s interpreter, and

, V8’s newest optimizing compiler. These technologies

to those of you who have followed the V8 blog over the last few years, but the switch to the new pipeline marks a big new milestone for both.

This guide is unlike others I’ve done so far, and has a bit of a narrative to go along with the sketches. I thought the entire concept of garbage collection and how it gets dealt with in javascript, or more specifically in engines that run javascript, deserves a bit more of an explanation. I would also like to mention that this guide is meant to be beginner friendly, and does not cover every aspect of memory management within V8, and the rest of V8 internals. I’ve added a bunch of resources, if you want to delve into it more. This guide also focuses on ✨ javascript ✨, , obviously garbage collection is different in things like C.